ISO 12958-2:2020 PDF

Overview

ISO 12958-2:2020 specifies a performance test method to determine the constant-head in-plane water flow capacity of geotextiles and geotextile-related products. The standard defines how to measure volumetric flow per unit width under representative field-like conditions using project-specific boundary materials (for example soils), a range of normal compressive stresses, seating times and low hydraulic gradients. It is intended to assess short- to mid-term performance (including primary creep effects) and to evaluate how contact with soils or confinement affects the product’s transmissivity.

Key Topics and Requirements

• Test principle: measure steady-state flow within the plane of the geotextile at a constant head loss under defined stresses, gradient and boundary conditions.
• Apparatus: constant-head in-plane flow cell capable of maintaining precise head loss; minimum useful dimensions (cell width ≥ 0.2 m, effective flow length ≥ 0.3 m); discharge head ≤ 100 mm.
• Loading and control: loading mechanism must hold normal compressive stress with ≤1% or 1 kPa error; hydraulic head measurement requirements vary by gradient (pressure transducers required for gradients